Melt fabricable polyesters containing at least 85 mole % of 3-hydroxy,4'-(4-hydroxyphenyl)benzophenone and at least 85 mole % of the diacid of p-phenylene, 2,6-naphthalene, or p,p'-bi-phenylene, are known in the art and are described in Irwin U.S. Pat. No. 4,245,082. Films prepared from the polyester polymers of Irwin cannot be biaxially oriented. U.S. Pat. No. 4,224,433 to Calundann et al. discloses wholly aromatic polyesters in which approximately 15 to 30 mole percent of the units polymerized may be a mixture of isophthalic acid and terephthalic acid.